The present invention relates to electronic ballasts for gas discharge lamps and, more particularly, to a method of configuring ballasts for use with different types of gas discharge lamps.
Many types of gas discharge lamps are in common use, including mercury vapor lamps, low pressure and high pressure sodium lamps and fluorescent lamps. HID lamps or Mercury Vapor Lamp is a gas discharge lamp which uses mercury in an excited state to produce light. The arc discharge is generally confined to a small fused quartz tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear or coated with a phosphor; in either case, the outer bulb provides thermal insulation, protection from ultraviolet radiation, and a convenient mounting for the fused quartz arc tube. Mercury vapor lamps (and their relatives) are often used because they are relatively efficient while offering better color rendition than either low- or even high-pressure sodium vapor lamps. Mercury vapor lamps also feature a very long lifetime.
HID lamps or Mercury vapor lamps, like fluorescent usually require a starting mechanism. In this case, though, the starting mechanism is usually contained within the mercury vapor lamp itself. Two main types of starting mechanism are pulse start lamps and probe start lamps. The pulse start lamp has only 2 electrodes, and they require a significant voltage pulse (typically 4 KV) in order to start the lamp. Probe start lamps contain a third electrode mounted near one of the main electrodes and connected through a resistor to the other main electrode. When power is applied, there is sufficient voltage to strike an arc between the starting electrode and the adjacent main electrode. The arc discharge produced eventually provides enough ionized mercury to strike an arc between the main electrodes. Occasionally, a thermal switch is installed to short the starting electrode to the adjacent main electrode, completely suppressing the starting arc once the main arc strikes.
A lamp closely related to the mercury vapor lamp is the Metal halide lamp which uses various other elements in an amalgam with the mercury. Sodium iodide and Scandium iodide are commonly in use. Metal halide lamps produce a much better quality light without resorting to phosphors. If Metal Halide lamps use a starting electrode, there is a thermal shorting switch to eliminate any electrical potential between the main electrode and the starting electrode once the lamp is lit. An electrical potential in the presence of the halides can cause the failure of the glass/metal seal). More modern metal halide systems do not use a separate starting electrode; instead, the lamp is started using high voltage pulses as with high-pressure sodium vapor lamps (Pulse start lamps).
LPS Lamps (Low Pressure Sodium) consist of an outer vacuum envelope of glass coated with an infrared reflecting layer of indium (allows the light wavelengths out and keeps the infrared (heat) in). The LPS lamp has an inner borosilicate 2 ply glass U shaped tube containing sodium metal and a small amount of neon and argon gas to start the gas discharge,
High pressure Sodium (HPS) lamps are smaller and contain some other elements (e.g. mercury), produce a dark pink glow when first struck, and produce a pinkish orange light when warmed up.
A gas discharge lamp is a negative resistance device and therefore requires auxiliary electronics, i.e. a ballast to prevent the lamp from destroying itself. An electronic ballast uses solid state electronic circuitry to provide the proper starting and operating electrical condition to power the gas discharge lamp. Electronic ballasts are generally smaller and lighter, function cooler and more efficiently than electromagnetic ballasts.
In addition to the type of gas discharge lamp, there is a wide range of power ratings, varying typically between 20 and 2000 watts. Consequently, a supplier of lamps and ballasts needs to stock hundreds of different ballasts, each ballast with its own part number for supporting all the different types of gas discharge lamps and all the available power ratings. Moreover, electronic ballast may include many features built in such as dimming control, depth of dimming level, time to dimming from start, number of ignition trials, total interval for ignition trials, temperature range, input voltage range, ballast parameter changes (for example to adapt the ballast to new lamps, etc.
There is thus a need for, and it would be highly advantageous to have a method of configuring a ballast part to support as required different types of gas discharge lamps of different power ratings. By stocking a single part number, a considerable savings in logistics costs is achieved.
The terms “distributor”, “reseller” and “customer” are used herein interchangeably and refers to either a wholesaler or a final consumer of ballast products and/or employees thereof and/or another acting on behalf of the distributor.
The terms “configuration” and “reconfiguration” are used herein interchangeably.